thermal properties of frozen ground
Link: http://w3id.org/permafrost/v/ipaglossary/t0363
Within: IPA Permafrost Glossary
Definition: The properties of the ground governing the flow of heat through it, and its freezing and thawing conditions.
| Term |
thermal properties of frozen ground
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propriétés thermiques du gélisol fr |
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| Comment |
The position of the interface between thawed and frozen soil with respect to the ground surface, for a given surface-temperature regime, depends on the thermal properties of the strata located above and immediately below the interface. The basic thermal properties of frozen ground are thermal conductivity, heat capacity and latent heat of fusion. Thermal conductivity is a measure of the quantity of heat that will flow through a unit area of a substance in unit time under a unit temperature gradient. Heat capacity (specific heat) is the amount of heat required to raise the temperature of a unit mass of a substance by one degree (sensible heat capacity). Volumetric heat capacity is the amount of heat required to raise the temperature of a unit volume of a substance by one degree. It is equal to the heat capacity multiplied by the density. Because the phase change in frozen soils is often gradual and continuous, the term "apparent heat capacity" is introduced to designate the rate of change of the total heat content (sensible plus latent heat) with temperature. The volumetric latent heat of fusion is the amount of heat required to melt the ice (or freeze the water) in a unit volume of soil. When phase change occurs over a temperature range, the latent heat manifests itself as an apparent (large) increase in heat capacity. Thermal diffusivity is defined as the ratio of the thermal conductivity to the volumetric heat capacity. It expresses the facility with which a material will undergo temperature change. These thermal properties vary with phase composition and hence temperature, soil type, total water content, porosity, degree of saturation, density and organic content.
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| dcterms:source |
https://doi.org/10.4224/20386561
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